In the thick of the National League East race, Miami has pulled the trigger on promoting its top prospect, calling up lefty Andrew Heaney from Triple-A New Orleans.

Miami had been planning on giving the 23-year-old Heaney one more Triple-A start, which would have come on Thursday. Instead, Heaney has been called up to help a struggling rotation. He will make his MLB debut on Thursday against the Mets at Marlins Park.

"Obviously, I check the scores every day," Heaney said. "I see how the big club is doing. Everybody does. Everybody is excited. It seems like a positive atmosphere that everybody is positive about the team, and wanting to win. I don't want to hold them back. I want to contribute. That's my main goal, to help this team win games."

The Marlins have also called up right-hander Anthony DeSclafani, who was scratched from his Triple-A start on Sunday. DeSclafani, who made two starts at the big league level in May, will take over the rotation spot of Jacob Turner, who is moving to the bullpen.

DeSclafani, acquired from the Blue Jays in November of 2012, will start on Tuesday at home against the Cubs.

"There's been a lot of speculation about Andrew Heaney over the last couple of weeks," Miami manager Mike Redmond said. "His day has arrived.

"We felt like bringing the younger guys here, it was the right time. Hopefully, they'll come out and stabilize our rotation and have success and help us win ballgames. That's the deal."

Outfielder Jake Marisnick and first baseman Justin Bour were also called up from New Orleans. Marisnick was in the starting lineup in center field and leading off on Monday in the series opener with the Cubs.

On a busy day, Miami also placed outfielder Christian Yelich on the 15-day disabled list, retroactive to Saturday, with a lower back strain. Infielder Donovan Solano was optioned to Triple-A New Orleans.

Catcher Jarrod Saltalamacchia was transferred to the 15-day disabled list after he had been on the seven-day disabled list with concussion symptoms since June 1.

Saltalamacchia began his rehab assignment with Class A Jupiter on Monday. There is no timetable for his return.

"We're not going to rush him back before he's ready to be back," president of baseball operations Michael Hill said.

Hill noted that in his 20 years in professional baseball, he doesn't recall four players from the same Minor League team, in this case, New Orleans, all being on the same flight to join the big league club. In all, nine roster moves were made.

Yelich, who experienced back spasms on Friday night, is not expected to be out longer than his 15 days.

The headliner of the afternoon is Heaney, the most hyped Miami pitch prospect since Jose Fernandez.

Heaney, the ninth overall pick in the 2012 First-Year Player Draft, is ranked as the No. 1 prospect in Miami's system and No. 25 in the game by MLB.com. He's also considered MLB's No. 1 left-handed pitching prospect.

"Jose Fernandez is Jose Fernandez, and Andrew Heaney is Andrew Heaney," Hill said. "We love them both and we're glad that we have them both. We're going to allow Andrew to grow and hopefully have a lot of success at the Major League level."

One reason for the urgency to add Heaney is that Fernandez is out for the season after undergoing Tommy John surgery in May.

"You're never going to replace Jose, but you want to try every day to give yourself a chance to win games," Hill said. "That's all we tried to do. We felt Wolf was a solid stopgap option for us. He had some good starts and he had some not so good starts."

Heaney, a former Oklahoma State standout, was 3-0 with a 2.74 ERA in four starts for New Orleans. He opened the season at Double-A Jacksonville, where he went 4-2 with a 2.35 ERA.

Giving Heaney Triple-A innings is a change from past philosophy, where the organization regularly promoted its young pitchers from Double-A.

"I'm really glad that happened," Heaney said. "There is a noticeable difference, I felt, from Double-A to Triple-A -- versus guys at Double-A that maybe have hundreds of professional at-bats, versus Triple-A, where you've got guys who have been in the big leagues, or who may be on rehab assignment or who may be ready to get called up. They may have thousands of professional at-bats. They'd have a different approach than some of the guys at Double-A. I think I learned a lot from there."

Not overpowering, Heaney relies on movement and possesses three plus-pitches: a fastball, slider and changeup. His velocity ranges 90-94 mph, and he occasionally will reach 95.

"I don't want to preach about velocity," Heaney said. "Velocity, it doesn't matter. Some guys throw 100 and it looks like 90. Some guys can throw 90 and it looks like 100. It's all about what the hitter perceives. If you've got good movement against any hitter, they say 90 with movement is going to be a lot harder to hit than 100 straight.

"You've just got to work in and out and throw strikes down in the zone, and let your fastball work for you. It doesn't really matter how hard you throw."

Miami headed into Monday night's action one game behind the Braves in the NL East, but the Marlins have been struggling to find quality starting pitching. Heaney and DeSclafani are two highly successful prospects.

Turner had been lined up to face the Cubs on Tuesday, but the right-hander has struggled of late. In his last start, on Wednesday at Texas, he worked four innings and gave up five earned runs. In his last three starts, he threw 14 1/3 innings, allowing 14 runs.

Out of options, the Marlins can't send Turner down to work on things. He now gets to pitch out of the bullpen, basically taking over the role Slowey had.

"He's going to be available for two or three innings -- whatever we need," Redmond said. "But at the same time, too, we may use him for short stints as well."

Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.